This invention relates to the operation of an ink jet of the type utilized in printing, and more particularly, to determine when the ink is present at the orifice of an ink jet.
Ink jets of various kinds including impulse jets require, from time-to-time, the priming and/or purging of the ink jet. During priming, ink is supplied to the ink jet to ready the ink jet for printing. During such priming, the ink jet is filled with ink until ink emerges at the orifice of the ink jet. Similiarly, during purging of the ink jet, ink is supplied to the jet until ink emerges from the orifice.
In certain instances, particularly after priming with an impulse ink jet, it is desirable to know when the ink jet has been fully primed; i.e., when ink first appears at the orifice of the ink jet so that priming may be discontinued on a timely basis before any ink is spilled from the orifice. In addition, it is desirable to discontinue priming on a timely basis so as to avoid the accumulation of a large amount of ink at the orifice which could, upon initiation of the ink jet, create a blotch on the printing medium.
Prior art efforts have been made to control the quantity of ink utilized in priming and thereby prevent the spillage and/or undesirable accumulation of ink at the orifice of an ink jet. For example, U.S. Pat. No. 2,997,180 to Zenner discloses an automatic priming device for an ink jet printer comprising a bladder of predetermined size which is filled with ink which is used during priming to supply ink to the ink jet orifice. However, as Zenner indicates, the size of the bladder must be carefully controlled to assure the proper amount of ink which will vary as a function of the capacity of the ink reservoir, the ink jet, and the connections between the ink reservoir and the ink jet.